Inflated Rubber Culvert Balloon

Inflatable rubber mandrels, also known as culvert balloons or pneumatic tubular formwork. These are expandable and contractible cylindrical bladders used in construction to create hollow spaces in concrete components. They are made from synthetic and natural rubber with a fiber-reinforced layer, giving them strength, elasticity, and flexibility. When used, compressed air is injected to expand the mandrel, which can withstand the pressure of concrete. They are used as a replacement for traditional formwork made of wood, bamboo, or steel. In addition to culvert construction, they are used in other fields like hydraulic and power engineering.